The most common type of EMI occurs in the radio frequency (RF) range of the electromagnetic (EM) spectrum, from 10 KHz to 77 GHz. This energy can be radiated by computer circuits, radio transmitters, fluorescent lamps, electric motors, internal combustion engines, lightning, and many other sources.
Device failures caused by interference—or “noise”—from electromagnetic energy are increasing due to the growing number of products that contain sensitive electronic components. The smaller size and faster operating speeds of these components make it more challenging to manage EM pollution. Increased device frequencies over 10 GHz are now common, resulting in proportionally decreased wavelengths that can penetrate very small openings in housings or enclosures.
Increasingly strict regulations address device emissions. At the same time, a product’s immunity to external EMI determines its commercial success or failure. To comply with regulations on both emissions and susceptibility, designers and manufacturers integrate shielding in their product designs through a working knowledge of EMI behavior and shielding techniques.